1. Field of the Invention
The embodiments of the present invention relate generally to coiled tubing units utilizing a direct drive tubing reel assembly.
2. Description of the Related Art
Oftentimes in the development and production of an oil or gas well, elongated tubing is inserted into the well from the surface for such purposes as the injection of certain types of fluids for stimulation of the production, displacing fluids in the well, for performing cleaning operations on the production tubing, as well as various other purposes. A continuous length of tubing is inserted into the well from a large reel at the surface. In the oil and gas industries, this process is known as coiled tubing.
A coiled tubing reel assembly includes a reel (otherwise known in the industry as a spool or wheel) on which the tubing is spooled, a stand for supporting the reel on which the tubing is stored, a drive system for rotating the reel and creating back-tension during operation of the reel, and a swivel assembly (typically hydraulic) to connect the coiled tubing to a fluid source/hydraulic pumps. The drive system is typically a chain driven system or a direct drive system, each having their own advantages/disadvantages which are commonly known in the industry.
Conventional designs of tubing reel assemblies, such as chain driven tubing reel assemblies and direct drive tubing reel assemblies, have significant issues in reel replacement in the situation where a different size coiled tubing must be used. Specifically, for changing a small-sized coiled tubing to large-sized coiled tubing and vice versa, the bore size of the hydraulic swivel would be an issue because of the sudden area change (expansion or contraction) at the swivel and coiled tubing. To solve these sudden expansion or contraction issues, using a proper size hydraulic swivel that has similar bore size with coiled tubing is preferred. However changing the hydraulic swivel to one with a proper bore size on a conventional tubing reel assembly is often difficult or impossible. Additionally, the tubing reel assembly may have a plumbing issue because the connection is typically located at the inside of the reel.
For the reasons included above, it is therefore an object of embodiments of the present invention to provide a tubing reel assembly that permits easier reel and hydraulic swivel replacement as well as easier maintenance for the entire assembly.